When the user draws with the ink tool and then tries to select something else, the ink disappears. All other modifications to the pdf are still present. The InkAdded event should fire when this happens. However, that is tied to when the user adds a signature. Weird, but even more so is the "SfPdfViewer.AnnotationSettings.Ink.Color" which will change the ink, not the signature.
Did i miss something? This seems wrong.
Open a pdf and select the ink tool. Draw something. Click the bottom left to exit the tool and poof, the ink is gone.